/*
    * Copyright 2001-2008 The Apache Software Foundation.
    * 
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * 
    *      http://www.apache.org/licenses/LICENSE-2.0
    * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   */
  
  package org.apache.juddi.keygen;
  
  import org.apache.commons.configuration.ConfigurationException;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.juddi.ClassUtil;
  import org.apache.juddi.config.AppConfig;
  import org.apache.juddi.config.Property;
  
  /**
   * Used to create the org.apache.juddi.keygen.KeyGenerator implementation
   * as specified by the 'juddi.keygenerator' property. Defaults to
   * org.apache.juddi.cryptor.DefaultKeyGenerator if an implementation is not
   * specified.
   *
   * @author <a href="mailto:jfaath@apache.org">Jeff Faath</a>
   */
  public abstract class KeyGeneratorFactory {
  	private static Log log = LogFactory.getLog(KeyGeneratorFactory.class);
  
  	// Key Generator default implementation
  	public static final String DEFAULT_IMPL = "org.apache.juddi.keygen.DefaultKeyGenerator";
  
  	// the shared Key Generator instance
  	private static KeyGenerator keyGenerator = null;
  
  	/*
  	 * Returns a new instance of a KeyGenerator.
  	 * 
  	 * @return KeyGenerator
  	 */
  	public static synchronized KeyGenerator getKeyGenerator() {
  		if (keyGenerator == null)
  			keyGenerator = createKeyGenerator();
  		return keyGenerator;
  	}
  	
  	public static synchronized KeyGenerator forceNewKeyGenerator() {
  		keyGenerator = null;
  		keyGenerator = createKeyGenerator();
  		return keyGenerator;
  	}
  
  	/*
  	 * Returns a new instance of a Cryptor.
  	 * 
  	 * @return Cryptor
  	 */
  	private static synchronized KeyGenerator createKeyGenerator() {
  		if (keyGenerator != null)
  			return keyGenerator;
  	
  		// grab class name of the Cryptor implementation to create
  		String className = System.getProperty(Property.JUDDI_KEYGENERATOR);
                  if (className==null){
                      try {
                              // grab class name of the Authenticator implementation to create
                              className = AppConfig.getConfiguration().getString(Property.JUDDI_KEYGENERATOR, DEFAULT_IMPL);
                      }
                      catch(ConfigurationException ce) {
                              log.error("Configuration exception occurred retrieving: " + Property.JUDDI_KEYGENERATOR);
                      }
                  }
                  try {
                      // write the Cryptor implementation name to the log
                      log.debug("Configuration Key Generator Implementation = " + AppConfig.getConfiguration().getString(Property.JUDDI_KEYGENERATOR));
                  } catch (ConfigurationException ex) {
                  }
                  log.debug("SysProp Key Generator Implementation = " + System.getProperty(Property.JUDDI_KEYGENERATOR));
                  log.debug("Using Key Generator Implementation = " + className);
  	
  		Class<?> keygenClass = null;
  		try {
  			// Use Loader to locate & load the Key Generator implementation
  			keygenClass = ClassUtil.forName(className,KeyGeneratorFactory.class);
  			// try to instantiate the Key Generator implementation
  			keyGenerator = (KeyGenerator)keygenClass.newInstance();
  		} catch(ClassNotFoundException cnfe) {
  			throw new RuntimeException("The specified Key Generator class '" + className + "' was not found on classpath.",cnfe);
  		} catch(InstantiationException ie) {
  			throw new RuntimeException("The specified Key Generator class '" + className + "' cannot be instantiated.",ie);
  		} catch(IllegalAccessException iae) {
 			throw new RuntimeException("The specified Key Generator class '" + className + "' cannot be instantiated due to illegal access.",iae);
 		} catch(Exception e) {
 			throw new RuntimeException("Exception while attempting to instantiate the implementation of Key Generator: " + className + "\n" + e.getMessage());
 		}
 	
 		return keyGenerator;
 	}
 }